The present invention is directed to a multiple-part fastener for holding together in a locked condition two mating parts such as two sheets of metal and more particularly, to a fastener which will lock two flat elements together where there is no access to the area behind one of the flat elements, such fastener generally, being referred to as a "blind" fastener.
Fastening members which are designed for use in the above-cited condition are well-known in the art. Fasteners of this type are usually constructed of a central member having a collapsible portion to allow the fastener to be inserted within the aperture of the mating work pieces with the collapsible portion being released after insertion to allow the fastener to be anchored to the work pieces. Examples of this type of fastener may be found in U.S. Pat. Nos. 3,905,270, 3,643,296, 3,939,752 and 3,815,182. The fasteners disclosed in these patents are of very simple construction since once mounted they are not removable. When the fasteners are required to be removable, the construction of such fasteners becomes quite complicated and expensive. An example of this type of fastener construction can be found in U.S. Pat. No. 3,705,442. Another drawback of this type of removable fasteners that are presently available is that each fastener is constructed to be mounted within a predetermined size aperture, thereby requiring different diameter fasteners be produced to accommodate various size apertures and thus further increasing the cost of the fastener. It is therefore a principal object of this invention to provide a fastener for holding two or more mating surfaces together in a locked or fastened position which is simple in construction and therefore low in cost. It is a further object of this invention to provide a fastener which is capable of functioning in a situation wherein the aperture is blind and there is a requirement that the fastener be removable for further use. It is another object of this invention to provide a fastener which will fasten two mating parts under compression so as to withstand vibrations. It is a still further object of this invention to provide a fastener which is able to function in a variety of aperture diameters.